In the related art, solid state imaging elements such as a CMOS (Complementary Metal Oxide Semiconductor) image sensor, and a CCD (Charge Coupled Device) image sensor are widely used in digital still cameras, digital video cameras, or the like. In addition, in recent years, CMOS image sensors are often adopted for solid state imaging elements installed in mobile apparatuses such as mobile phone apparatuses provided with an imaging function, from the viewpoint that the power supply voltage is low and the power consumption is low.
For example, in the CMOS image sensor, the charge, which is photoelectrically converted by the PD (Photodiode) included in a pixel, is transferred to the FD (Floating Diffusion) which is a floating diffusion region. Furthermore, by measuring the potential of the FD, a pixel signal of a level corresponding to the charge generated by the PD is read out.
Generally, the CMOS image sensor may only perform read-out of the pixel signal for one row of pixels at a time, therefore, it is not possible to provide synchronicity of the exposure time of the screen. In relation to this, for example, according to a technology of reading out a pixel signal known as “global shutter”, a CMOS image sensor provided with synchronicity of exposure time of the screen is being developed. In the related art, in order to realize the global shutter, it is necessary to provide a shielded charge holding region in the pixels, and to hold the pixel signal in the charge holding region in pixels which are waiting for read-out of the pixel signal. As this charge holding region, an FD provided in a pixel is often used.
In addition, the present applicant proposes a solid state imaging element which avoids a reduction in saturation charge amount by using both a CCD-type memory section and an FD as the charge holding region (for example, refer to PTL 1).